Paginating a Detail view in Django - django

Question

I'm new to Django and for my first project I'm building a portfolio. And I need a little kick-start with pagination help. I have an "index" view with a list of projects and a detail view of each project. In the detail view, I want a feature to be able to paginate between each individual object. I've gone through the Pagination documenation and applied what I learned with my index view but when I try to do the same thing with my detail view I get a TypeError saying my "object of type 'Project' has no len().
Here's a sample of my views.py code for reference:
def index( request ):
all_projects = Project.objects.all().order_by( '-pub_date' )
paginator = Paginator( all_projects, 12 )
try:
page = int( request.GET.get( 'page','1' ))
except ValueError:
page = 1
try:
projects = paginator.page( page )
except (EmptyPage,InvalidPage):
projects = paginator.page( paginator.num_pages )
return render_to_response( 'portfolio/index.html', { 'all_projects':all_projects, 'projects':projects, 'MEDIA_URL':MEDIA_URL })
def detail( request, project_id ):
project = get_object_or_404( Project, id=project_id )
return render_to_response( 'portfolio/detail.html', { 'project':project, 'MEDIA_URL':MEDIA_URL } )
Apologies if I sound n00b-ish because I am, and gratitude in advance for any help. Also, I read this previous post but it didn't seem to apply to me because my views aren't Class-based.

Answer 1

Django has built-in get_next_by_FOO()/get_previous_by_FOO() methods which will return the next/previous object depeding on a datetime-field.
You could access them in the template by somethow like:
{{ project.get_next_by_pub_date.title }}
I would say that this is the preferred method over using pagination for that, as you will get a nice url you can define in your model's get_absolute_url for every item!
To paginate you need an instance of a QuerySet, not an object! So you should replace your get_object_or_404 call by a filter/all. So it would be basically the same as the list view, but just pass the number 1 to the paginator, as you already do!

Answer 2

I actually do not have that setup through Django's pagination. I used this code:
prev_issue = Issue.objects.filter(title=title).filter(number__lt=issue.number).order_by('-number')[:1]
next_issue = Issue.objects.filter(title=title).filter(number__gt=issue.number).order_by('number')[:1]
In your case, I would do something like this, but you would have to filter by something, too:
prev_project = Project.objects.order_by('-pub_date')[:1]
next_project = Project.objects.order_by('pub_date')[:1]
Then put the two in the context.
I also recommend django-pagination. I notice you probably want the pagination to stay on the index, correct? http://code.google.com/p/django-pagination/
You just have to mess with the template codes and it works great.

Answer 3

The great thing about Django is, that there is code for nearly every common programming problem, that you can download and use in your own project. (and most of the django packages are quiet well written too)
for pagination check out http://pypi.python.org/pypi/django-pagination
it's really easy to install and setup, so you do not have to think about pagination and focus on coding your software!
hope this helps, Anton

Answer 4

In my views.py
def ProjectDetail(request,pk):
context = {}
template = 'views/projectdetail.html'
project = ''
prev = Project.objects.filter(pk__lt=pk).order_by('-pk')[:1]
next = Project.objects.filter(pk__gt=pk).order_by('pk')[:1]
try:
print(prev[0].pk)
print(next[0].pk)
except:
pass
project = Project.objects.filter(pk=pk)
context['categories'] = ProjectCategory.objects.all()
paginator = Paginator(project, 1) # Show 25 contacts per page
page = request.GET.get('page')
try:
data = paginator.page(page)
except PageNotAnInteger:
# If page is not an integer, deliver first page.
data = paginator.page(1)
except EmptyPage:
# If page is out of range (e.g. 9999), deliver last page of results.
data = paginator.page(paginator.num_pages)
if prev:
context['prev'] = prev[0].pk
if next:
context['next'] = next[0].pk
context['data'] = data
return render_to_response(template, context,context_instance=RequestContext(request))
in my template i have
<div class="row">
<a {% if next %} href="{% url 'task:project-detail' next %}" class="btn btn-primary pull-right" {% else %} class="btn btn-primary pull-right disabled" {% endif %}>Next</a>
<a {% if prev %} href="{% url 'task:project-detail' prev %}" class="btn btn-primary pull-left" {% else %} class="btn btn-primary pull-left disabled" {% endif %} >Previous</a>
</div>